1. Field of the Invention
The present invention relates to an organic light emitting apparatus for use in, for example, a light emission type display or a surface emitting light source.
2. Description of the Related Art
An inorganic material has been used for an inorganic moisture barrier layer in an organic light emitting device (which may hereinafter be abbreviated as “device”) of which the light emitting portion of an organic light emitting apparatus is formed because the inorganic material improves the durability of the device under various use environments, and is excellent in optical properties. The inorganic moisture barrier layer is required to provide a hard, dense film structure so as to cover the entirety of the device because the purpose of the layer is to prevent moisture or oxygen from penetrating into the device.
A conventionally known method of forming a hard, dense film is a film formation method involving the employment of a VHF plasma CVD method. The method has been employed as an approach to forming an inorganic moisture barrier layer without damaging an organic compound layer below the inorganic moisture barrier layer. The inorganic moisture barrier layer produced by this CVD method is formed of an inorganic material, and serves as a single film having high moisture barrier properties. However, the layer is apt to crack owing to an external impact because the layer is hard and dense. The generated crack serves as a defect, with the result that the moisture barrier properties of the layer are impaired in some cases.
In addition, in order to improve the productivity of a device, it is necessary that a large number of devices are integrated on a single substrate so that the tact time is shortened. Accordingly, a step of dividing the substrate on which the inorganic moisture barrier layer is formed may be included. A defect such as a crack in the inorganic moisture barrier layer generated at the time of the dividing step is responsible for a reduction in reliability of a device after the division. In view of the foregoing, various studies have been conducted on a production method for a device, the constitution of the device, etc. in order to prevent such defect.
Japanese Patent Application Laid-Open No. H10-074757 proposes the following method: for an inorganic moisture barrier layer excellent in adhesiveness and moisture resistance, an exposed portion of an SiON layer is subjected to an ammonia plasma treatment for the nitriding of an edge portion of top surface of the layer, whereby moisture is prevented from penetrating from the periphery of the layer.
Japanese Patent Application Laid-Open No. 2001-044141 proposes a method of preventing a crack from expanding toward a device on a GaAs substrate. A groove is formed by etching along a dicing line before the device is cut at its circumferential portion. Then, an insulating film made of SiN or the like is formed on the groove. Even when a crack is generated as a result of the segmentation of the device by dicing, a stress concentration on an R portion present in the groove, whereby the expansion of the crack is prevented.
Japanese Patent Application Laid-Open No. 2001-126866 proposes the following method: an organic EL device is sandwiched between two substrates by using a photocurable resin as an adhesive layer, a resin at a light emitting device portion is initially cured with light, and a cutting portion is divided by pushing without being cured, whereby the generation of a crack at the uncured cutting portion is prevented.
However, the technique disclosed in Japanese Patent Application Laid-Open No. H10-074757 is not preferable in terms of productivity because its purpose is the improvement of a moisture transmitting layer appearing as a result of the removal of the inorganic moisture barrier layer at a scribe line by etching, and it requires an increased number of steps including a step for the nitriding of the exposed portion of the inorganic moisture barrier layer. Therefore, it may be desirable to proceed to a breaking step after scribing without conducting an etching step.
On the other hand, the technique disclosed in Japanese Patent Application Laid-Open No. 2001-044141 is a method of stopping the progress of a crack generated in an inorganic moisture barrier layer by causing a stress to concentrate on a folded point in the inorganic moisture barrier layer. The method, which is applied to a cutting method such as dicing in the given example, is also applicable to scribing. However, the need for forming a groove by etching in a substrate for providing the inside of the inorganic moisture barrier layer with a folded point reduces productivity. In addition, it is difficult to form a groove on, for example, a glass substrate. The inventors of the present invention have paid attention to the circumstance that losses in terms of an improvement in productivity and of reliability may be caused in the case where a cutting surface is treated by using another step so that a structure having high moisture barrier properties is provided, or where a structure that hardly cracks owing to cutting is provided by another step.
Further, the technique disclosed in Japanese Patent Application Laid-Open No. 2001-126866, which does not related to a silicon compound, is a method of preventing defects upon cutting such as chipping and cracking by letting the hardness of the photocurable resin layer on a light emitting layer differ from that on a cutting surface. However, a difference between the hardness of an inorganic moisture barrier layer formed of an inorganic material before curing and that after the curing is smaller than in the case of an organic substance such as a resin, so the prevention of defects cannot be expected.